A silver halide photographic material which can be rapidly processed and has excellent color-reproducibility has been highly demanded and tone-reproducibility in recent years.
With regard to rapid processability, silver halide photographic materials are continuously processed by automatic processors employed in modern processing laboratories. Processed prints are delivered to users in the course of the day on which they are received, as an improved in service to users. Furthermore, finished prints are demanded several hours after being submitted for processing. The need for rapid processing is increasing.
A reduction in processing time produces an improves production efficiency and reduces production costs. Accordingly, the development of rapid processing techniques is urgently in demand.
Rapid processing has been approached with regard to both photographic materials and processing solutions. In order to accelerate color development, it has been proposed to elevate the temperature of the processing solutions, to increase the pH of the processing solutions and to add highly concentrated color developing agents. Furthermore, additives such as developing accelerators have been employed.
1-Phenyl-3-pyrazolidone described in U.K. Patent 811,185, N-methyl-p-aminophenol described in U.S. Pat. No. 2,417,514 and N,N,N',N'-tetramethyl-p-phenylenediamine described in JP-A-50-15554 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") are known developing accelerators.
However, satisfactory rapid processing cannot be achieved by these methods and photographic characteristics are often deteriorated. For example, the fog level is often increased.
The development rate is greatly affected by the shape, size and composition of the silver halide grains comprising the silver halide emulsion of the photographic material. Particularly, the development rate is greatly influenced by the halogen composition. A remarkably high development rate is obtained when silver halide emulsions having a high silver chloride content are used.
In silver halide color photographic materials, dye image is typically formed by reducing the exposed silver halide grains with an aromatic primary amine color developing agent, and than reacting the oxidation product of the developing agent with couplers previously incorporated in the color photographic material. Generally, three kinds of couplers forming dyes of yellow, magenta and cyan are used to effect color reproduction by subtractive color photography.
Various factors must be satisfied to effect better color reproduction. Namely, the level of color reproduction varies depending on the spectral sensitivity interlaminar effect of the photographic material for photographing, the matching of spectral sensitivity of the color print material with the dye images formed in the photographic material for photographing, the overlap in spectral sensitivity of sensitive layers having different color sensitivity, the spectral absorption characteristics of formed dyes, and color mixing between sensitive layers forming different dyes in processing.
Tone reproduction is also an important factor for improving image quality. Furthermore, gray gradation as well as color gradation is an important factor.
Improvements in the quality of color photographs in recent years are mostly attributable to improvements in the multi-layer effects of photographic materials for photographing, and these improvements contribute much to an improvement in color reproducibility. Such photographic materials, however, may not have sufficient color gradation.
New systems have been developed and are being used wherein photographic materials having a high silver chloride content as described above are used in combination with processing solutions free from sulfites or benzyl alcohol once contained in conventional color developing solutions for color paper.
Photographs obtained from high silver chloride color paper adapted for rapid processing are advantageous in that high silver chloride content silver halides or silver chloride does not substantially absorb light in the visible region, and the sensitivity inherent in silver chloride does not damage the discrimination function with regard to red light sensitivity, green light sensitivity and blue light sensitivity, such that , color mixing does not result. On the other hand, silver chloride emulsions are disadvantageous in that color gradation in high density area in particular is deteriorated as compared with the use of a conventional silver chlorobromide emulsion. Good color gradation without detriment to rapid processability or the other advantages of silver chloride or highsilver chloride content emulsions is highly desired.
This problem is liable to be caused when color gradation of the original having red color is to be reproduced, and is evident in color paper containing silver chloride.
Pyrazoloazole magenta dye-forming couplers hereinafter, "magenta couplers", have been widely used in addition to 5-pyrazolone couplers for conventional color papers in recent years. Couplers of this type, especially the 5-pyrazolone couplers, form dyes having good spectral absorption characteristics, good fastness to light, exhibit little stain due to the couplers alone, and are practically advantageous. These couplers are described in U.S. Pat. Nos. 3,369,879 and 3,725,067, Research Disclosure 24220 (June 1984), ibid., 24230 (June 1984), U.S. Pat. Nos. 4,500,630 and 4,540,654, JP-A-61-65245, JP-A-61-65246, JP-A-61-147254 and European Patent 0,226,849. Among these pyrazoloazole magenta couplers, pyrazolo[5,1-c][1,2,4]triazoles and pyrazolo[1,5-b][1,2,4]triazoles are preferred from the viewpoint of overall performance in color formation, spectral absorption characteristics of the formed dyes and image fastness. Particularly, the pyrazolo[1,5-b][1,2,4]triazoles described in U.S. Pat. No. 4,540,654 are preferred. Couplers of this type having branched alkyl groups as described in JP-A-61-65245, sulfonamido groups as described in JP-A-61-65246, alkoxysulfonamido groups as described in JP-A-61-147254 and alkoxy or aryloxy groups introduced at the 6-position of as described in European Patent 0,226,849 are particularly preferred.
However, it has been found that when these couplers are used for the green light-sensitive silver halide emulsion layers, the above-described unsatisfactory color gradation is more noticeable, even though use of the capless is advantageous in other respects.
Accordingly, when the pyrazoloazole magenta couplers are used in color paper containing a silver halide emulsion having a high silver chloride content, unsatisfactory color gradation is liable to occur and became pronounced.
Color gradation may be improved as described, for example, in JP-B-58-10737 (the term "JP-B" as used herein means an "examined Japanese patent application") wherein a sensitive layer which forms a black dye image is provided. However, the material cost is increased, because an extra sensitive layer must be provided. In addition, the method is disadvantageous in that the processing time is increased due to an increase in the thickness of the coated layer of the photographic paper. JP-B-58-10737 is silent regarding rapid processing or the improvement of chroma. JP-A-61-91657 (U.S. Pat. No. 4,806,460) discloses a method for improving the tone reproducibility of a colored image by adding a dye image having a different hue exceeding a specific density of a color image. However, this method does not teach compatibility with rapid processing using high content silver chloride emulsions. Furthermore, this method does not suggest means for improving the expression of color gradation while improving color reproducibility, by raising chroma with pyrazoloazole magenta couplers.